Adjunctive vein of marshall ethanol infusion for pulmonary vein isolation in unilateral left pulmonary artery agenesis: a case report.

Background: Isolated unilateral agenesis of the pulmonary artery (UAPA) is an exceptionally rare congenital anomaly. In adults, it may promote structural remodelling and predispose to atrial fibrillation (AF). Pulmonary vein (PV) isolation in UAPA poses unique challenges due to anatomical variations, hypoplastic pulmonary veins (PVs), and altered venous drainage, potentially reducing ablation efficacy. Case summary: An 80-year-old woman with persistent AF and heart failure, and left UAPA, underwent PV isolation using a size-adjustable cryoballoon (POLARx FIT, Boston Scientific, Marlborough, MA, USA). Computed tomography demonstrated the absence of the left pulmonary artery and systemic collateral supply to the left lung. Left superior PV (LSPV) occlusion with a 31-mm cryoballoon achieved complete contrast seal (nadir -56°C) but failed electrical isolation. A subsequent 28-mm application with similar occlusion and nadir temperature achieved isolation with a prolonged time-to-isolation of 97 s. The hypoplastic left inferior PV (LIPV) was not ablated to avoid stenosis risk. During a second procedure, LSPV reconnection and residual LIPV potentials were detected. Ethanol infusion into the vein of Marshall (VOM) successfully isolated both veins. Discussion: In UAPA, extensive systemic collateral circulation to the affected lung may cause heat dissipation ('heat sink effect'), limiting the efficacy of thermal energy delivery. Moreover, hypoplastic PVs carry an increased risk of stenosis after thermal ablation. Additional non-thermal lesion-creation techniques, such as VOM ethanol infusion, may be necessary to achieve durable and safe isolation when conventional thermal methods are insufficient.